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TCA9617B: What signal would appear on A side when no VCCA bias voltage?

Jason Dai
Expert 3720 points

Part Number: TCA9617B

Hello E2E,

Due to possible power sequence issue in customer system, the bias voltage for VCCA as A side may delay for a while after VCCB even EN ready.

Our question is that what is the behavior at SDA_A and SCL_A pins when (1) VCCB get ready but EN low, (2) both VCCB and EN get ready?

Sincerely,

Jason

  • 0
    TI__Guru 53535 points

    Hi Jason,

    If the A-side of this device is pulled-up to VccA, SDA_A and SCL_A will remain LOW until the power rail is ready. TCA9617 will not attempt to propagate this LOW to the B-side of the device because the input-low voltage threshold is referenced to the supply (which would still be disabled). However, to avoid possible glitches from occurring during the power ramp of VccA, it is recommended that EN be kept disabled until both power-rails are ready. All outputs are disabled when EN is LOW. 

    Let me know if you have any more questions.

    Regards,
    Eric